· Decision 1 · Week 2

"How does data live in tables?"

Before any query, before any design — you need a mental model of how relational data sits in tables, how rows connect through keys, and how SELECT pulls it back out.

Tables Primary Keys Foreign Keys Foundational

Why this decision matters

Every other topic in this course depends on this one. If you don't have a clear picture of what a table is, what a row is, and what a key does, every JOIN, every constraint, and every design choice later will feel like guessing. We start with a visual tool (Microsoft Access) and the same tool the Fortune 500 uses (Oracle APEX), so you can see the same concepts in two very different environments.

By the end of this topic you'll be able to

Read and create a table; identify primary keys and foreign keys in an existing schema; run a SELECT against an Access database and an Oracle APEX workspace; explain to a non-technical colleague how relational data is organized.

Materials

Key concepts to know
  • Table, row, column — the three primitives. Get fluent in the vocabulary.
  • Primary key — the unique identifier for a row. Single or composite.
  • Foreign key — a column that points to a primary key in another table. The glue of relational data.
  • Data types — VARCHAR, INT, DATE, DECIMAL, BOOLEAN. Why picking the right one matters.
  • NULL — not zero, not empty string, not "no" — it means "we don't know." Behaves weirdly; learn its rules.
  • SELECT, FROM, WHERE — the query you'll write 80% of the time.
Practice databases (Access)

Two flavors of the classic Northwind sample database. Open in Microsoft Access to explore tables, keys, and run your first queries visually.

Hands-on worksheet
Translating business questions to queries

The hardest part of basic SQL isn't the syntax — it's translating "the boss wants to know X" into the right query. This worksheet drills that skill.

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